.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
.\" and Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(GPLv2+_DOC_ONEPARA)
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" the License, or (at your option) any later version.
.\" %%%LICENSE_END
.\"
.\" References consulted:
.\"   GNU glibc-2 source code and manual
.\"   Dinkumware C library reference http://www.dinkumware.com/
.\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
.\"   ISO/IEC 9899:1999
.\"
.TH TOWLOWER 3  2021-03-22 "GNU" "Linux Programmer's Manual"
.SH NAME
towlower, towlower_l \- convert a wide character to lowercase
.SH SYNOPSIS
.nf
.B #include <wctype.h>
.PP
.BI "wint_t towlower(wint_t " wc );
.BI "wint_t towlower_l(wint_t " wc ", locale_t " locale );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR towlower_l ():
.nf
    Since glibc 2.10:
        _XOPEN_SOURCE >= 700
    Before glibc 2.10:
        _GNU_SOURCE
.fi
.SH DESCRIPTION
The
.BR towlower ()
function is the wide-character equivalent of the
.BR tolower (3)
function.
If
.I wc
is an uppercase wide character,
and there exists a lowercase equivalent in the current locale,
it returns the lowercase equivalent of
.IR wc .
In all other cases,
.I wc
is returned unchanged.
.PP
The
.BR towlower_l ()
function performs the same task,
but performs the conversion based on the character type information in
the locale specified by
.IR locale .
The behavior of
.BR towlower_l ()
is undefined if
.I locale
is the special locale object
.B LC_GLOBAL_LOCALE
(see
.BR duplocale (3))
or is not a valid locale object handle.
.PP
The argument
.I wc
must be representable as a
.I wchar_t
and be a valid character in the locale or be the value
.BR WEOF .
.SH RETURN VALUE
If
.I wc
was convertible to lowercase,
.BR towlower ()
returns its lowercase equivalent;
otherwise it returns
.IR wc .
.SH VERSIONS
The
.BR towlower_l ()
function first appeared in glibc 2.3.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR towlower ()
T}	Thread safety	MT-Safe locale
T{
.BR towlower_l ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
.BR towlower ():
C99, POSIX.1-2001 (XSI);
present as an XSI extension in POSIX.1-2008, but marked obsolete.
.PP
.BR towlower_l ():
POSIX.1-2008.
.SH NOTES
The behavior of these functions depends on the
.B LC_CTYPE
category of the locale.
.PP
These functions are not very appropriate for dealing with Unicode characters,
because Unicode knows about three cases: upper, lower, and title case.
.SH SEE ALSO
.BR iswlower (3),
.BR towctrans (3),
.BR towupper (3),
.BR locale (7)
.SH COLOPHON
This page is part of release 5.13 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
